Since the 9/11/2001 terrorist attacks on U.S. soil, research related to national security within the nation's airports has advanced. Numerous studies focus on the capabilities and limitations of the airport's security screener's, which essentially perform an inspection process. There is a strong history of inspection literature, in manufacturing or non-destructive inspection, found within both Industrial Engineering and Psychology that could provide further insight into the nature of security inspection. This work establishes a background of the existing Industrial Engineering and Psychology literature related to both general and security inspection, through the application of Pasteur's Quadrant (Stokes, 1997) and the TOMES model. From this model application, a selection of factors was further explored through four independent fully self-contained studies. The first study considered a formal validation of x-ray security as an inspection task, furthering the link between security inspection and the more general inspection literature. Widely accepted and proven outcomes of general inspection, such as probability of detection (PoD) curves and speed-accuracy trade-offs are explored. The second study considered vigilance changes in an x-ray inspection task utilizing actual security screeners through both a continuous 4-hour task and throughout a typical workday. The third study investigated image enhancements utilizing novice participants in a simulated x-ray screening task. Novices investigated images in six different image enhancements: Original, Grayscale, Negative, Super Enhancement, Organic Only and Organic Stripping. The final study investigated expertise through a meta-analysis of 15 studies investigating security inspection of luggage post September 2001. Both training and experience, as measured by days on job, were compared. All together this work established the validity of security inspection as a general inspection task and investigated various security inspection factors utilizing principles of both industrial engineering and psychology. Insight into factor effects was gained providing further information regarding the nature of security inspection.